//filename: AbstractRenderer.java
public abstract class AbstractRenderer
implements GLSurfaceView.Renderer
{
   public void onSurfaceCreated(GL10 gl, EGLConfig eglConfig) {
      gl.glDisable(GL10.GL_DITHER);
      gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT,
      GL10.GL_FASTEST);
      gl.glClearColor(.5f, .5f, .5f, 1);
      gl.glShadeModel(GL10.GL_SMOOTH);
      gl.glEnable(GL10.GL_DEPTH_TEST);
   }

   public void onSurfaceChanged(GL10 gl, int w, int h) {
      gl.glViewport(0, 0, w, h);
      float ratio = (float) w / h;
      gl.glMatrixMode(GL10.GL_PROJECTION);
      gl.glLoadIdentity();
      gl.glFrustumf(-ratio, ratio, -1, 1, 3, 7);
   }

   public void onDrawFrame(GL10 gl)
   {
      gl.glDisable(GL10.GL_DITHER);
      gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
      gl.glMatrixMode(GL10.GL_MODELVIEW);
      gl.glLoadIdentity();
      GLU.gluLookAt(gl, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
      gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
      draw(gl);
   }

   protected abstract void draw(GL10 gl);
}